Class-Imbalanced Learning

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Overview

It studies how skewed class frequencies, long tails, and rare events bias models toward majority classes, a challenge in medical diagnosis, fraud detection, and computer vision. Common approaches rebalance data through over- or undersampling and synthetic examples, adjust objectives with class weights, focal or logit-adjusted losses, and improve representations with prototypes, contrastive learning, or class-aware sampling. Active learning, calibration, and federated or semi-supervised methods address settings with limited labels, distributed data, or shifting class priors. Results depend strongly on data structure and deployment conditions: reweighting and synthetic data can improve minority recall but may also harm performance or calibration, so evaluations need class-wise and operational metrics, not accuracy alone.

Latest papers

CardsList

260 papers23 papers in the last four weeks, down 4% on the four weeks before. 0.1% of all new papers.

  1. H-SemiS: Hierarchical Fusion of Semi and Self-Supervised Learning for Knee Osteoarthritis Severity Grading

    Apr 25, 2026Chandravardhan Singh Raghaw, Anushka Parwal, Shahid Shafi Dar +2Class-Imbalanced LearningSelf-Supervised Learning

    Department of Computer Science and Engineering, Indian Institute of Technology Indore, Indore 453552, India · Department of Computer Science and Engineering, National Institute of Technology Tiruchirappalli, Tiruchirappalli 620015, India

  2. Modulation Feature Enhancement with a Multi-Stage Attention Network for Underwater Acoustic Target Recognition

    Apr 24, 2026Jiaping Yu, Shefeng Yan, Linlin Mao +2Class-Imbalanced Learning

  3. Generating Synthetic Malware Samples Using Generative AI

    Apr 23, 2026Tiffany Bao, Kylie Trousil, Quang Duy Tran +2Class-Imbalanced LearningSynthetic Data Augmentation

    Department of Computer Science, Boston University, Boston, MA 02215, USA · Department of Computer Science, University of Wisconsin–La Crosse, La Crosse, WI 54601, USA · Department of Computer Science, San José State University, San Jose, CA 95192, USA +2

  4. Improving Facial Emotion Recognition through Dataset Merging and Balanced Training Strategies

    Apr 22, 2026Serap KırbızClass-Imbalanced LearningFacial Expression Recognition

    aMEF University,Department of Electrical and Electronics Engineering, Huzur Mah. Maslak Ayaza˘ga Cad. No:4 Sarıyer, ˙Istanbul, 34396, Türkiye

  5. RADS: Reinforcement Learning-Based Sample Selection Improves Transfer Learning in Low-resource and Imbalanced Clinical Settings

    Apr 22, 2026Wei Han, David Martinez, Anna Khanina +2Class-Imbalanced LearningFew-Shot Learning

    School of Computing Technologies, RMIT University · Department of Infectious Disease, Peter MacCallum Cancer Centre · 3National Centre for Infections in Cancer, Melbourne +2

  6. Model-Agnostic Meta Learning for Class Imbalance Adaptation

    Apr 20, 2026Hanshu Rao, Guangzeng Han, Xiaolei HuangClass-Imbalanced LearningInstance Reweighting

    University of Memphis

  7. Self-Reinforcing Controllable Synthesis of Rare Relational Data via Bayesian Calibration

    Apr 18, 2026Chongsheng Zhang, Hao Wang, Zelong Yu +7Class-Imbalanced LearningSynthetic Data Augmentation

    Henan University, China · Department of Statistics, LMU Munich · MCML Munich +1

  8. Learning Class Difficulty via Dynamic Focal Attention for Histopathology Segmentation

    Apr 15, 2026Lakmali Nadeesha Kumari Rathukohe Mudiyanselage, Sen-Ching Samson CheungHistopathology Image SegmentationClass-Imbalanced Learning

    University of Kentucky, Lexington, KY 40506, USA

  9. EigenCoin: sassanid coins classification based on Bhattacharyya distance

    Apr 13, 2026Rahele Allahverdi, Mohammad Mahdi Dehshibi, Azam Bastanfard +1Image ClassificationClass-Imbalanced Learning

    Department of Electrical, Computer and IT, Islamic Azad University, Qazvin Branch, Iran · Department of Computer Engineering, Islamic Azad University, Karaj Branch, Iran · National Museum of Iran, Tehran, Iran

  10. UniPROT: Uniform Prototype Selection via Partial Optimal Transport with Submodular Guarantees

    Apr 13, 2026Prateek Chanda, Prayas Agrawal, Karthik S. Gurumoorthy +3Class-Imbalanced LearningSubmodular Optimization

    Department of Computer Science and Engineering, Indian Institute of Technology Bombay · Microsoft Research India · Walmart Global Tech, India +2

  11. WBCBench 2026: A Challenge for Robust White Blood Cell Classification Under Class Imbalance

    Apr 12, 2026Xin Tian, Xudong Ma, Tianqi Yang +4White Blood Cell ClassificationMedical Image Classification

    University of Oxford, Oxford, United Kingdom · University College London, London, United Kingdom · University of Bristol, Bristol, United Kingdom +1

  12. Dynamic Class-Aware Active Learning for Unbiased Satellite Image Segmentation

    Apr 10, 2026Gadi Hemanth Kumar, Athira Nambiar, Pankaj BodaniActive LearningRemote Sensing Image Segmentation

    Department of Computational Intelligence, Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India · Space Applications Centre, Indian Space Research Organisation, Ahmedabad, India

  13. Retrieval Augmented Classification for Confidential Documents

    Apr 9, 2026Yeseul E. Chang, Rahul Kailasa, Simon Shim +2Retrieval-Augmented ClassificationText Classification

    Department of Security Convergence, Chung-Ang University, Seoul, South Korea · Department of Applied Data Science, San Jose State University, San Jose, CA, United States · Department of Industrial Security, Chung-Ang University, Seoul, South Korea

  14. From Selection to Scheduling: Federated Geometry-Aware Correction Makes Exemplar Replay Work Better under Continual Dynamic Heterogeneity

    Apr 9, 2026Zhuang Qi, Ying-Peng Tang, Lei Meng +4Federated Continual LearningReplay-Based Continual Learning

    School of Software, Shandong University, China · College of Computing and Data Science, Nanyang Technological University, Singapore · School of Computer Science and Technology, Harbin Institute of Technology, China

  15. Needle in a Haystack: One-Class Representation Learning for Detecting Rare Malignant Cells in Computational Cytology

    Apr 9, 2026Swarnadip Chatterjee, Vladimir Basic, Arrigo Capitanio +2Whole-Slide Image AnalysisComputational Pathology

    Department of Information Technology, Uppsala University, Sweden · Department of Clinical Diagnostics, School of Health Sciences, Jönköping University, Sweden · Department of Pathology, Linköping University Hospital, Sweden

  16. CAMO: A Class-Aware Minority-Optimized Ensemble for Robust Language Model Evaluation on Imbalanced Data

    Apr 8, 2026Mohamed Ehab, Ali Hamdi, Khaled ShabanClass-Imbalanced LearningLanguage Model Ensembles

    Faculty of computer science, October University for Modern Science & Arts, Giza,Egypt. · Department of Computer Science and Engineering, Qatar University, Doha, Qatar.

  17. Robust Fair Disease Diagnosis in CT Images

    Apr 8, 2026Justin Li, Daniel Ding, Asmita Yuki Pritha +3Group Distributionally Robust OptimizationFairness in Medical Image Classification

    Carmel High School, Carmel, Indiana, USA · Capstone School Dhaka, Bangladesh · Clarkstown High School South, West Nyack, New York, USA +2

  18. RPM-Net Reciprocal Point MLP Network for Unknown Network Security Threat Detection

    Apr 8, 2026Jiachen Zhang, Yueming Lu, Fan Feng +3Network Intrusion DetectionOOD Detection

    School of Cyberspace Security, Beijing University of Posts and Telecommunications · Guangxi Key Laboratory of Digital Infrastructure, Guangxi Zhuang Autonomous Region Information Center

  19. Sparsity-Aware Voxel Attention and Foreground Modulation for 3D Semantic Scene Completion

    Apr 7, 2026Yu Xue, Longjun Gao, Yuanqi Su +23D Scene Completion3D Scene Understanding

    Xi’an Jiaotong University, China

  20. Beyond Imbalance Ratio: Data Characteristics as Critical Moderators of Oversampling Method Selection

    Apr 6, 2026Yuwen Jiang, Songyun YeClass-Imbalanced LearningClassification

    School of Artificial Intelligence, Guangzhou Institute of Science and Technology, Guangzhou, China

  21. A Data-Centric Vision Transformer Baseline for SAR Sea Ice Classification

    Apr 3, 2026David Mike-Ewewie, Panhapiseth Lim, Priyanka KumarRemote SensingVision Transformer

    Department of Computer Science, The University of Texas Permian Basin, Odessa, Texas, USA

  22. AstroConcepts: A Large-Scale Multi-Label Classification Corpus for Astrophysics

    Apr 2, 2026Atilla Kaan Alkan, Felix Grezes, Sergi Blanco-Cuaresma +5AstrophysicsMulti-Label Classification

    Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA · Faculty of Psychology, UniDistance Suisse, Brig, Switzerland

  23. A Self supervised learning framework for imbalanced medical imaging datasets

    Apr 2, 2026Yash Kumar Sharma, Charan Ramtej Kodi, Vineet PadmanabhanSelf-Supervised LearningMedical Image Classification

    Artificial Intelligence lab, School of Computer & Information Sciences, University of Hyderabad, Hyderabad 500046, India

  24. Quantum-Inspired Geometric Classification with Correlation Group Structures and VQC Decision Modeling

    Apr 2, 2026Nishikanta Mohanty, Arya Ansuman Priyadarshi, Bikash K. Behera +1Tabular ClassificationHybrid Quantum-Classical ML

    Centre for Quantum Software and Information, University of Technology Sydney, 15 Broadway, Ultimo, Sydney, 2007, NSW, Australia. · Bikash’s Quantum (OPC) Pvt. Ltd., Balindi, Mohanpur, 741246, WB, India. · Universit`a degli Studi di Cagliari, Via Is Mirrions, Cagliari, 09123, Italy.

  25. Perturb-and-Restore: Simulation-driven Structural Augmentation Framework for Imbalance Chromosomal Anomaly Detection

    Apr 1, 2026Yilan Zhang, Hanbiao Chen, Changchun Yang +10Medical Image Anomaly DetectionSynthetic Anomaly Generation

    Computer Science Program, Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia · Center of Excellence on Smart Health (KCSH) and Center of Excellence for Generative AI, KAUST, Thuwal 23955-6900, Saudi Arabia · Guangdong Provincial Maternal and Child Health Hospital, Guangzhou 511442, China +1

  26. Toward Optimal Sampling Rate Selection and Unbiased Classification for Precise Animal Activity Recognition

    Apr 1, 2026Axiu Mao, Meilu Zhu, Lei Shen +3Animal Behavior AnalysisAdaptive Sampling

    School of Communication Engineering, Hangzhou Dianzi University, Hangzhou 310018, China · Department of Mechanical Engineering, City University of Hong Kong, Hong Kong SAR 999077, China · Department of Electrical and Computer Engineering, The University of Hong Kong, Hong Kong SAR 999077, China +3

  27. Class-Distribution Guided Active Learning for 3D Occupancy Prediction in Autonomous Driving

    Mar 28, 2026Wonjune Kim, In-Jae Lee, Sihwan Hwang +2Active Learning3D Occupancy Prediction

    Robotics Program, KAIST, Daejeon 34141, South Korea · Interdisciplinary Program in Artificial Intelligence, Seoul National University, Seoul 08826, South Korea · Graduate School of Mobility, KAIST, Daejeon 34051, South Korea +1

  28. Accurate Precipitation Forecast by Efficiently Learning from Massive Atmospheric Variables and Unbalanced Distribution

    Mar 27, 2026Shuangliang Li, Siwei Li, Li Li +3Precipitation ForecastingClass-Imbalanced Learning

    Hubei Key Laboratory of Quantitative Remote Sensing of Land and Atmosphere, School of Remote Sensing and Information Engineering, Wuhan University, Wuhan, 430079, China · Perception and Effectiveness Assessment for Carbon-neutrality Efforts, Engineering Research Center of Ministry of Education, Institute for Carbon Neutrality, Wuhan University, Wuhan, 430072, China · Hubei Meteorological Information and Technology Support Center, Wuhan, 430074, China

  29. Uncertainty-Guided Label Rebalancing for CPS Safety Monitoring

    Mar 26, 2026John Ayotunde, Qinghua Xu, Guancheng Wang +1Class-Imbalanced LearningCyber-Physical Systems

    Lero Research Ireland Centre for Software Research, University of Limerick, Castletroy, Limerick, Ireland. · the University of Ottawa, Canada, and Lero Research Ireland Centre for Software Research, University of Limerick, Ireland.

  30. Positive-First Most Ambiguous: A Simple Active Learning Criterion for Interactive Retrieval of Rare Categories

    Mar 25, 2026Kawtar Zaher, Olivier Buisson, Alexis JolyActive LearningFine-Grained Image Retrieval

    INRIA, LIRMM, Université de Montpellier, France · Institut National de l’Audiovisuel, France